Rouhani, a moderate, was a key architect of the 2015 nuclear deal with the United States, the European Union and other partners and his first term was marked by an emergent international engagement.

More than 40 million Iranian voters flocked to polling stations Friday, and by Saturday morning more than 25 million votes had been counted, according to the head of Iran's Interior Ministry State Elections Committee.

No sitting President has failed to win a second term since 1981 and Rouhani's engagement with the outside world resonated with voters who have disliked the country's isolation., CNN reported.